Seed Rain Produced by Bats and Birds in Forest Islands in a Neotropical Savanna1

The high degree of isolation of forest “islands” relative to “continental” forested areas creates a naturally fragmented landscape in the savanna ecosystem. Because fragmentation can affect the intensity and quality of biological interactions (e.g., seed dispersal) we examined the abundance and species richness of seed rain produced by birds and bats in three different parts of forest islands (center, edge, and exterior) located at the Estación Biológica del Beni, Bolivia. Despite the fact that we found higher species density of seeds in the seed rain at the center of forest islands, when comparing species richness corrected for observed differences in density, species richness was higher at the edge of islands. The three parts of the islands did not differ in total number of seeds. Three genera (Byrsonima, Ficus, and Piper) contributed the most seeds to the seed rain. We found differences in the abundance of dispersed seeds probably because of the variation related with the disturbance line, where the savanna matrix interacts with the forest islands. Carollia perspicillata, Carollia brevicauda, and Sturnira lilium were the bats that contributed most to seed dispersal within forest islands, and Schistochlamys melanopis and Tyranneutes stolzmanni were the most important birds. The movement of seeds produced by bats and birds within forest islands of the savanna is crucial to assure the continuity of ecological process and dynamics of these forest islands.     

Seed Dispersal by Birds and Bats in Lowland Philippine Forest Successional Area

In the tropical forests of SE Asia, only a few studies have dealt with the role animal dispersal plays in early forest succession and rehabilitation, and a comparison of bird and bat dispersal is even rarer. We investigated seed dispersal by birds and bats in a successional area in the lowland dipterocarp forest of the Subic Watershed Forest Reserve (SWFR) in Luzon Island, Philippines. Using pairs of day and night traps, we collected seeds during 3 mo of wet season and 3 mo of dry season in a 1.2-ha study site. Bird-dispersed seeds predominated over those dispersed by bats in terms of both seed abundance and number of seed species. The most abundant endozoochorous seed species were significantly biased toward either bird or bat dispersal. Birds and bats appeared to compete more strongly for fruit resources during the dry season than during the wet season, and bats responded more to changes in the seasons than birds did. GLM analyses showed that the factor that had the strongest influence on overall seed distribution was the number of fleshy-fruited trees surrounding the traps, and that the distribution pattern of day-dispersed seeds was affected by more physical factors (number of trees, size of trees, presence of fleshy-fruited and conspecific trees) in the study site than the pattern of night-dispersed seeds were. Given that birds are the more important dispersers in the study site, restoration efforts in SWFR might benefit by focusing on attracting these dispersers into its degraded habitats.     

The Role of Arboreal Seed Dispersal Groups on the Seed Rain of a Lowland Tropical Forest1

Most tropical plants produce fleshy fruits that are dispersed primarily by vertebrate frugivores. Behavioral disparities among vertebrate seed dispersers could influence patterns of seed distribution and thus forest structure. This study investigated the relative importance of arboreal seed dispersers and seed predators on the initial stage of forest organization–seed deposition. We asked the following questions: (1) To what degree do arboreal seed dispersers influence the species richness and abundance of the seed rain? and (2) Based on the plant species and strata of the forest for which they provide dispersal services, do arboreal seed dispersers represent similar or distinct functional groups? To answer these questions, seed rain was sampled for 12 months in the Dja Reserve, Cameroon. Seed traps representing five percent of the crown area were erected below the canopies of 90 trees belonging to nine focal tree species: 3 dispersed by monkeys, 3 dispersed by large frugivorous birds, and 3 wind‐dispersed species. Seeds disseminated by arboreal seed dispersers accounted for ca 12 percent of the seeds and 68 percent of the seed species identified in seed traps. Monkeys dispersed more than twice the number of seed species than large frugivorous birds, but birds dispersed more individual seeds. We identified two distinct functional dispersal groups, one composed of large frugivorous birds and one composed of monkeys, drop dispersers, and seed predators. These groups dispersed plants found in different canopy strata and exhibited low overlap in the seed species they disseminated. We conclude it is unlikely that seed dispersal services provided by monkeys could be compensated for by frugivorous birds in the event of their extirpation from Afrotropical forests.     

Small Tent-Roosting Bats Promote Dispersal of Large-Seeded Plants in a Neotropical Forest

In Neotropical regions, fruit bats are among the most important components of the remaining fauna in disturbed landscapes. These relatively small-bodied bats are well-known dispersal agents for many small-seeded plant species, but are assumed to play a negligible role in the dispersal of large-seeded plants. We investigated the importance of the small tent-roosting bat Artibeus watsoni for dispersal of large seeds in the Sarapiquí Basin, Costa Rica. We registered at least 43 seed species > 8 mm beneath bat roosts, but a species accumulation curve suggests that this number would increase with further sampling. Samples collected beneath bat feeding roosts had, on average, 10 times more seeds and species than samples collected 5 m away from bat feeding roosts. This difference was generally smaller in small, disturbed forest patches. Species-specific abundance of seeds found beneath bat roosts was positively correlated with abundance of seedlings, suggesting that bat dispersal may influence seedling recruitment. Our study demonstrates a greater role of small frugivorous bats as dispersers of large seeds than previously thought, particularly in regions where populations of large-bodied seed dispersers have been reduced or extirpated by hunting.     

Frugivory and Seed Dispersal by Four Species of Primates in Madagascar's Eastern Rain Forest1

In the unique faunal assemblage of the Malagasy rain forest, lemurs appear to play particularly important roles as seed-dispersing frugivores. A three-month study of feeding ecology and seed dispersal by four species of lemurs in Madagascar's eastern rain forest found that three species, Eulemur rubriventer, Eulemur fulvus, and Varecia variegata were seed dispersers, and the fourth, Propithecus diadema, was a seed predator. In germination trials, seeds passed by lemurs sprouted significantly faster and in greater numbers than those not passed by lemurs. Analysis of fruit morphologies of 69 local plant taxa producing fleshy fruits during the study period found that these fruits fell into two well-defined color categories that correlated significantly with fruit size. Seventy seven percent of fleshy fruits greater than 10 mm in diameter were colored green, brown, tan, purplish, or black, while all fruits less than 10 mm in diameter were colored red, yellow, orange, pink, blue, or white. Three introduced exotic plant species provided exceptions to this pattern, producing fruits which were larger than 10 mm and pink or orange. Fruits chosen by the primates in this study were usually larger than 10 mm in diameter and were in nearly all cases colored green, brown, tan, purplish, red, or some combination of these colors. Morphological traits shared by fruits of multiple plant taxa in the diets of seed-dispersing lemurs suggest possible coevolved relationships between Malagasy rain forest plants and lemurs.     

食肉质果鸟对种子的传播作用

食肉质果鸟对种子的传播作用鲁长虎常家传（东北林业大学,哈尔滨１５００４０）ＥｆｆｅｃｔｏｆｔｈｅＦｌｅｓｈｙ＿ｆｒｕｉｔｓＥａｔｉｎｇＢｉｒｄｓｏｎＳｅｅｄＤｉｓｐｅｒｓａｌ．ＬｕＣｈａｎｇｈｕ,ＣｈａｎｇＪｉａｃｈｕａｎ（ＮｏｒｔｈｅａｓｔＦｏ...     

食干果鸟对种子传播的作用

食干果鸟对种子传播的作用鲁长虎袁力（东北林业大学,哈尔滨１５００４０）ＥｆｆｅｃｔｏｆＤｒｙ＿ｆｒｕｉｔＥａｔｉｎｇＢｉｒｄｓｔｏＳｅｅｄＤｉｓｐｅｒｓａｌ．Ｌｕｃｈａｎｇｈｕ,ＹｕａｎＬｉ（ＮｏｒｔｈｅａｓｔＦｏｒｅｓｔｒｙＵｎｉｖｅｒｓｉｔｙ,...     

Dung Beetle Communities and Seed Dispersal in Primary Forest and Disturbed Land in Amazonia1

Seeds from tropical fruiting trees ingested and defecated on the soil surface by primary dispersers (such as primates) are vulnerable to destruction from rodents, insects, and fungi. Burial by dung beedes as an incidental result of their feeding and nesting activities often provides these seeds with refugia from attack. To examine the effect of habitat disturbance on the dung beetle communities involved in this process, I surveyed dung beedes at three sites in the Amazon basin, in die states of Parí, Amazonas, and Rondónia, Brazil. Through principal component analysis on measurements of size and behavioral characters of beedes, I determined the relative quality of beetle species as seed dispersers (dispersal defined as horizontal or vertical movement of seeds) and ranked them into seed dispersal guilds. I used correspondence analysis to examine in what habitats (primary forest or varying degrees of disturbed habitat) these guilds were abundant. Most guilds decreased with increasing habitat disturbance, but one guild made up of large nocturnal burrowers (primarily Dichotomius) became more abundant with increasing disturbance (up to the level of highest disturbance surveyed), at which point all dung beede species became scarce. Clear–cuts had lower species richness, lower abundance, and lower biomass dian forested areas. These results imply that clear–cutting is detrimental to all seed dispersal dynamics in tropical rain forests, but that some levels of disturbance allow enough disperser activity to preserve this ecosystem function.     

Use of Fruiting Trees by Birds in Continuous Forest and Riparian Forest Remnants in Los Tuxtlas,Veracruz, Mexico1

The composition of plant species in fragmented landscapes may be influenced by the pattern of visitation by birds to fruiting trees and by the movement of seeds among and within fragments. We compared bird visitation patterns to two tree species (Dendropanax arboreus, Araliaceae; Bursera simaruba, Burseraceae) in continuous forest and remnants of riparian vegetation in a region dominated by pasture in Los Tuxtlas, Veracruz, Mexico. We quantified frequency of visitation, fruit consumption, consistency of visitation (percentage of total tree observation periods during which a given bird species was recorded), and species composition of birds at individuals of both tree species in continuous forest and riparian remnants. Bird visitation rate, species richness, and fruit consumption rates were similar within both tree species in the two habitats. Species assemblages at D. arboreus were different between continuous forest and remnants. Species assemblages at B. simaruba did not differ by habitat. Our results demonstrate that habitat disturbance may influence avian visitation patterns, which may in turn affect subsequent recruitment patterns in some tree species. Our results, however, were not consistent between the tree species, suggesting that it is difficult to generalize concerning the effects of forest disturbance on avian species assemblages in fruiting trees.     

Seed Dispersal of a High Quality Fruit by Specialized Frugivores: High Quality Dispersal?1

Dispersal quality, as estimated by the cumulative effects of dispersal, germination, seed predation, and seedling survival, was examined for Beilschmiedia pendula (Lauraceae) in Monteverde, Costa Rica. I determined the pattern of dispersal by finding seeds deposited by birds, protected the seeds from seed predators with cages to assess germination and seedling survival, and examined seed predation rates with marked seeds. Seed predation, germination, and seedling survival were compared between seeds naturally dispersed by birds and seeds placed at randomly located sites. Approximately 70 percent of seeds dispersed by birds (N= 244) were deposited <10 m from crown edges of fruiting B. pendula trees, although some seeds were dispersed at least 70 m away. Larger seeds were more likely to be dispersed under or close to the parent trees, and larger seeds produced larger seedlings. Seed size was not correlated directly with seedling survival, but larger seedlings at three months were most likely to survive one year. Seed predation by mammals and insects and seedling mortality due to fungal pathogens were concentrated beneath the crowns of parent trees. Seedlings and saplings were more abundant beneath fruiting B. pendula trees, but individuals farther away were taller on average. Thus, dispersal is beneficial for B. pendula, but such benefits appear most pronounced at a small spatial scale; seeds dispersed >30 m from the crown edges actually had a lower probability of survival than those dispersed 10–20 m. Only 10 percent of B. pendula. seeds received high‐quality dispersal in terms of landing in the zone with the highest per seed probability of seedling survival 10–20 m from parental crowns.     

The Bushmeat Harvest Alters Seedling Banks by Favoring Lianas, Large Seeds, and Seeds Dispersed by Bats, Birds, and Wind

We evaluated predictions that hunters favor lianas, large seeds, and seeds dispersed by bats, small birds, and mechanical means for seedling banks in central Panama. We censused 3201 trees in 20 1-ha plots and 38,250 seedlings in the central 64 m² of each plot. We found significant differences in the species composition of the seedling bank between nine protected sites in the Barro Colorado Nature Monument and 11 hunted sites in the contiguous Parque Nacional Soberanía. Lianas, species with large seeds, and species with seeds dispersed by bats, small birds, and mechanical means were all overrepresented at hunted sites. The latter two findings could also be evaluated relative to the species composition of reproductively mature adults for canopy trees. The tree species present in the seedling bank had significantly heavier seeds than the tree species present as adults at hunted sites but not at protected sites. The representation of seed dispersal modes among the species present in the seedling bank did not reflect pre-existing differences in the local species composition of adults. We hypothesize that hunting large seed predators favors large seeds by reducing predation and increasing survival. We also hypothesize that the harvest of large birds and mammals that disperse many seeds favors other species whose seeds are dispersed by bats, small birds, and mechanical means. This process also favors lianas because the seeds of disproportionate numbers of liana species are dispersed by wind.     

Diets of Frugivorous Bats in Montane Rain Forest and Coffee Plantations in Southeastern Chiapas,Mexico

Frugivorous are one of the main diaspore dispersers in tropical ecosystems, particularly in open areas and sites in the early stages of ecological succession. Frugivorous bat species respond differentially to habitat modification, and in the context of their diaspore dispersal functions it is important to understand species' ecological requirements. We compared the diversity of diaspores, obtained from fecal samples and from fruits carried by frugivorous bats, among five shaded coffee plantations under different management regimes and a montane rain forest in southeastern Chiapas, Mexico. At each site, bats were captured every 2 mo from March 2004 to July 2005, using six mist‐nets, during two consecutive nights. We captured 2589 individuals from 18 frugivorous species, from which we collected 969 fecal samples, containing 42 diaspore species associated with early and late successional plants. Although, we captured more frugivorous bat species in montane rain forest, the number of diaspore species in this site (N=14) was not significantly different from the coffee plantations under different management regimes (16–24). In montane rain forest, Sturnira ludovici fed mainly on Piper auritum, but in coffee plantations ate Peperomia sp., Saurauia madrensis, Solanum chrysotrichum and Solanum diphyllum. Artibeus jamaicensis and Artibeus intermedius feed mostly Cecropia obtusifolia and Ficus cookii in all coffee plantations. We suggest that the presence of frugivorous bats in shaded coffee plantations is favored by trees and shrubs associated with secondary and introduced vegetation that farmers have allowed to grow within or around the plantations.     

Natural Regeneration in Plantations of Native Trees in Lowland Brazilian Atlantic Forest: Community Structure,Diversity, and Dispersal Syndromes

Plantations of native‐tree species are often recommended for ecological restoration, but the understanding of how these techniques catalyze natural ecological processes is limited. We investigated natural regeneration in five plantations of native trees in the Poço das Antas Biological Reserve (PABR) in the state of Rio de Janeiro, Brazil. The plantations were 9–11 years old, and contained 8–14 native‐tree species with different compositions and relative density of species. We analyzed floristic composition, structure (density and basal area) of overstory and understory strata, as well as other ecological attributes (dispersal syndromes, fruit or seed size, and the availability of fruit for frugivores). Zoochorous species comprised 77% of the community, with a prevalence of the two smallest size classes of propagules (< 0.6 and 0.6–1.6 cm) in natural regeneration. The density of zoochorous plants in the understory was positively correlated with their density in the overstory, indicating their influence on natural regeneration (r² = 0.36; p < 0.0002). Fruit availability for frugivores (density and richness of plants fruiting during the year) was also positively correlated with the density of stems in the understory. Therefore, attributes such as dispersal syndrome and fruiting season should be considered in selecting species to be planted. The differences in natural regeneration observed in each of the native‐tree plantations indicated that the performance of plantations as a restoration strategy may differ, depending on initial species composition, planting density, and site conditions.     

Seed Dispersal by Monkeys and the Fate of Dispersed Seeds in a Peruvian Rain Forest1

Primary seed dispersal by two species of monkeys and the effects of rodents and dung beetles on the fate of dispersed seeds are described for a rain forest in southeastern Perú. During the six-month study period (June–November 1992) spider monkeys (Ateles paniscus) dispersed the seeds of 71 plant species, whereas howler monkeys (Alouatta seniculus) dispersed seeds of 14 species. Spider and howler monkeys also differed greatly in their ranging behavior and defecation patterns, and as a consequence, produced different seed rain patterns. Monkey defecations were visited by 27 species of dung beetles (Scarabaeidae). Dung beetles buried 41 percent of the seeds in the dung, but the number of seeds buried varied greatly, according to seed size. Removal rates of unburied seeds by rodents varied between 63–97 percent after 30 d for 8 plant species. The presence of fecal material increased the percentage of seeds removed by seed predators, but this effect became insignificant with time. Although seed predators found some seeds buried in dung balls (mimicking burial by dung beetles), depth of burial significantly affected the fate of these seeds. Less than 35 percent of Brosimum lactescens seeds buried inside dung balls at a depth of 1 cm remained undiscovered by rodents, whereas at least 75 percent of the seeds escaped rodent detection at a depth of 3 cm and 96 percent escaped at 5 cm. Both dung beetles and rodents greatly affected the fate of seeds dispersed by monkeys. It is thus important to consider postdispersal factors affecting the fate of seeds when assessing the effectiveness of frugivores as seed dispersers.     

Seed Dispersal by Salvin's Curassow,Mitu salvini (Cracidae), in a Tropical Forest of Colombia: Direct Measurements of Dispersal Distance1

Seed dispersal by Salvin's curassows (Mitu salvini) was studied in a lowland tropical forest at La Macarena on the border of the Macarena and Tinigua National Parks, the Department of Meta, Colombia. Continuous observations were made on the feeding and ranging behavior of a well-habituated pair of birds from 0600 to 1800 h for 19 days. Ibtal observation time was 222 h. The daily distance traveled by the birds ranged from 630 to 3750 m, with a mean of 1959 m (± 776 m). The total home range was ca 34.4 ha. Although curassows were observed consuming fruits of 13 species belonging to the families Rubiaceae, Meliaceae, Moraceae, Burseraceae, Leguminosae, and Lecythidaceae, only seeds of Geophila re fens (Rubiaceae) and Picas spbenophylla (Moraceae) were found in their feces. For G. repens, the mean and maximum retention times were 1 h 52 min (± 1 h 20 min) and 6 h 08 min, and the mean and maximum direct dispersal distances were 245 m (± 164 m) and 633 m. More than half the seeds were dispersed in canopy gaps. For F. sphenophylla, the mean and maximum retention times were 3 h 1 5 mm (± .37 min) and 7 h 08 min, and the mean and maximum direct dispersal distances were 329 m (± 46 m) and 451 m. Nearly 60 percent of the estimated seed intake of G. repens and 92-94 percent of F. sphenophylla were digested or damaged. The retention times and the dispersal distances for Streptogyna americana, which has adhesive burrs, were also measured. The mean and maximum retention times were 1 h 55 min (± 1 h 56 min) and 9 h 11 min, and the mean and maximum direct dispersal distances were 128 m (± 68 m) and 280 m. This is the first study in which direct measurements were made for retention times and dispersal distances of the epizoochory and endozoochory for birds in the field.     

Patterns of Seed Dispersal and Dispersal Failure in a Hawaiian Dry Forest Having Only Introduced Birds

Dry forests are among the most endangered natural communities in the Hawaiian Islands. Most have been reduced to isolated trees and small forest fragments in which native tree species reproduce poorly. The replacement of native birds by introduced generalists may be contributing to dry forest decline through modification of seed dispersal patterns. To document seed dispersal by introduced birds, we conducted foraging observations on fleshy-fruited trees and measured seed rain under trees and in adjacent open areas for 1 year in a dry forest dominated by native trees. Although trees covered only 15.2 percent of the study area, 96.9 percent of the bird-dispersed seeds were deposited beneath them. The Japanese white-eye (Zosterops japonicus) was the principal dispersal agent. Among bird-dispersed seeds, those of the invasive tree Bocconia frutescens accounted for 75 percent of all seeds collected beneath trees (14.8 seeds/m²/yr) and the invasive shrub Lantana camara accounted for 17 percent. Although nearly 60 percent of the reserve's native woody species possess fleshy fruits, introduced birds rarely disperse their seeds. Native trees accounted for <8 percent of all bird-dispersed seeds and are consequently experiencing dispersal failure by falling directly under parent trees. Smaller-seeded non-native plants, in contrast, may be benefiting from dispersal by introduced birds. Current dispersal patterns suggest that these readily disseminated non-native plants may eventually replace the remaining native flora.     

The Effect of Dung and Dispersal on Postdispersal Seed Predation of Attalea phalerata (Arecaceae) by Bruchid Beetles1

Low postdispersal mortality of palm seeds in tapir dung is hypothesized to result from the mechanical barrier provided by dung against bruchid infestation and/or from the distance to adult palms at which seeds are dispersed. We tested these hypotheses by distributing endocarps of Attalea phalerata Mart. ex Spreng. in experimental dung piles in Beni, Bolivia. Predation rates were significantly lower for seeds covered by dung than for exposed or partially covered seeds, but did not differ between seeds placed below and 50 m away from palms. Thus, dung, not short‐distance dispersal, protects seeds against bruchid beetles, and may ultimately promote survival of palm seeds.